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Very slow cranking - Did I set my timing chain incorrectly?


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When I try to start my 1938 Buick Special (248 CI Straight eight) the engine cranks over VERY slowly and seems to drain the battery very quickly. I suspect there may be a problem with my timing which is causing the problem, and I was hoping for some guidance from my fellow pre-war enthusiasts. Here's some salient background info:

Engine was rebuilt totally in the early 70s. When I bought the car, the engine had been partially reassembled (block and valvetrain reassembled but no carb, generator, fuel pump, covers, etc on engine). I reassembled the rest and started it up for the first time EVER on the rebuild this past week. Seems to run well, but I haven't tried driving it yet so no comments on power. I'm only able to get it to start using starting fluid.

I have an Optima red top (6V) with a full charge. Same issue (slow cranking) was present with my last battery, a reproduction OEM unit bought from Cars, Inc.

Starter motor is freshly rebuilt, because I thought the slow cranking was due to a bad motor...guess not!

I have never touched the valves. No significant valve noise when the engine is running.

As part of reassembling the engine, I had to install the timing chain. It seem to me that having the timing chain off by a link or two could cause the slow cranking issue. I have some 37-38 engine data sheets (they were once spiral bound, I bought them off of eBay) which state that the chain should have "10 or 11" links between the timing marks on the cogs of the crankshaft and camshaft. My 38 Buick shop manual states 10 links. The accompanying picture in both the spiral bound sheets and the shop manual is identical and shows 11 links if you count the links sitting directly on top of the timing marks. This means the engine in the illustration has 9 links "between" the marks (i.e. not including the links sitting on the marks themselves). This seems like an odd discrepancy to me. In any case, I have my engine set up just like the illustration; 11 links including those on top of the marks, or 9 if you don't include them. Am I wrong?

I was hoping someone might have some suggestions for me about the slow cranking, whether my timing chain is set up correctly, etc. Thanks in advance!

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Even if the cam is off one tooth, the engine should crank the same speed! The engine might not idle as well or have the power expected, but the cranking RPM should not be affected. These engines don't turn over very fast ever.

It sounds to me that you have the cam timing proper.

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Do these old cars just crank that slowly in normal operation? I'm talking really slow, and maybe 10 seconds of cranking before the battery is exhuasted. Maybe when I work on the car tonight I'll time how long it takes to crank the rotor 360 degrees to give you guys a feeling for what I mean; I know "slow" is a relative term...

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You really need to get some running time on your engine before concluding it cranks too slow. Make sure you have decent battery cables, most folks recommend making your own from 00 welding cable. The cables available in most auto parts stores are great for 12V but marginal for 6V.

But, if you can get it running, accumulate some time on this engine. Make sure it has decent oil pressure and plenty of water. Get the generator working so it charges the batter. Expect that it will probably run hot at first due to all the friction in your engine. Just let it cool down and get it started again. After a few hours running, I'll bet it cranks and runs quite a bit better. As soon as possible, take it on short driving trips near your home.

If after all this it still cranks slowly, change those cables and question the Optima battery. Personally, I am no fan of the Optima 6V battery, even though many think they are wonderful. I have had two of them and they did not last or produce much sustained cranking power compared to lead/acid batteries.

Good luck and enjoy your break in period. Those straight eights are wonderful engines, smooth and powerful.....

Bill.

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Before throwing rocks at your rebuilding ability, try attaching a heavy duty jumper cable from the ground terminal of the battery to one of the starter attaching bolts.

Slow cranking is often due to a poor electrical ground,

Jon.

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Wow, thanks for all the responses and suggestions! I have some followup questions:

Battery cables: The cables I have now are from Bob's Automobilia, so I assume (always a dangerous word) that they are accurate replacements for the OEM cables. I was aware of the need to go with heavier cable for 6V, which is why I bought these from Bob's. If I were to replace them with the 00 welding cable, where would I find such cable? Would I have to special order it or would an automotive store carry it or...? I also like the idea of running a dedicated ground to the starter housing, I've had enough trouble with bad grounds on other cars that having a little "insurance" appeals to me.

Running time on the engine: Is there a prescribed "break in" method? It had occurred to me that the engine was likely "tight" since it was a rebuild with 0 hours. I have the generator/charging system working, and I'm getting good oil pressure. The cooling system seems to be working just fine (I had the engine running for about 15 minutes at fast idle last week).

Timing chain: It sounds like you guys don't think this is the cause of my problem. Regardless, any insight into whether my settings are correct? It just so happens that after my 15 minites of running last week I discovered an oil leak at the base of the timing cover from a significant rip in the pan gasket. I have dissected down to the cover in order to address this problem, so if I'm going to change the orientation of the chain this is a pefect time since I have the cover off anyway.

Thanks again for all of the insight, you guys have been extremely helpful!

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The advice about the battery cables is absolutely correct. The starter draws around 300A and there should be no more than a few tenths of a volt drop across the battery cables. Measure the voltage while cranking directly from the starter terminal to the starter housing.

A rebuilt engine will be very tight until there are a few thousand miles on it. If the ignition timing is too far advanced. This combined with a tight engine will make it almost impossible to turn over. Timing spec is I believe 4 deg BTDC, although there is an "octane selector" that allows up to 10 deg advance. Now with today's octane the timing can be advanced quite a bit without knocking but will make it hard to turn over especially when the engine is hot. Did you check the timing with a light at the flywheel?

A quick way to tell if the timing is too advanced is to temporarily jumper the coil negative to ground. If the engine cranks normally without ignition then the timing is too advanced.

Lastly break-in oil should be lightweight such at SAE20. If a SAE50 or wide range multiweight is used it will create additional drag.

Good luck,

Steve D

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I got my 00 cable from an authentic wiring harness maker that specializes in Packard wiring (I own a 1940 Packard). But I suppose if you wanted to make your own, the cable should be available from certain auto supply stores.

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<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Timing spec is I believe 4 deg BTDC, although there is an "octane selector" that allows up to 10 deg advance. </div></div>

is that 4 degrees achieved by advancing the octane selector at all, or is that the timing you get if you retard it all the way? i remember playing around with that when i first got this thing running and not knowing a thing about timing, and i wondered why when it was all the way to one side the engine turned so slow! so i put it somewhere about halfway because i liked the sound out of the exhaust better with it more to that side, but i wanted to be able to start it! <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

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The timing is set to 4 degrees with a timing light at the mark on the flywheel. There is a sheetmetal cover just above the starter that snaps off the flywheel housing to allow access to the indicator. Rotate the distributer to get 4 degrees with the vacuum advance line disconnected.

The octane selector scale is adjustable by a lock screw which holds it on the distributer base. Loosen the screw and set the scale to the center. The octane selector now indicates +/-10 deg from the nominal 4 degrees static timing.

Steve D

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Did Buick use a braided ground strap rather than a round cable? if so I would really recommend you go to tractor supply, NAPA, or a good auto electric supply and get a braided ground cable. They can carry a lot more current than most round wire. Make sure the ground connection is getting a good bite into unpainted metal. did your current cables get hot during cranking?

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I like the comments about batteries, cables and ignition timing. I remember going through the same confusion as you on the cam timing chain - sounds to me like you have it right.

My best success with batteries has been to go to the Interstate Battery dealer. Go to the guy on the industrial side of town, as he will service fork lift trucks, etc. They carry a battery with almost the same size case as the original, it may be about 3/4 inch taller. This is meant for industrial applications and has tons of capacity. Being the industrial-type retailer, he can also make up some 00 cables for you. I am now on my second battery from these guys, the first one lasted about 6 years. The guy commented that 3 or 4 years is more typical. Go to their website and search on 6V batteries. Note that if you search on '38 Buick you will get a slightly smaller capacity battery than if you just search on 6V.

Jeff

PS - I can take those pictures of the ends of the trunk latch mechanism for you.

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Buick used a round cable from the positive to the starter and a braided cable from the negative to the engine block. I got both of these through a Buick vendor many years ago but I don't remember who. You might be able to use welding cable for the positive(and negative if originality is not important) which uses very fine flexible wire and comes down to 0000 gauge.

Steve D

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I'd go with the braided strap. The round welding cable is fine, but inch for Amp you need a BIG diameter to get the current carrying capacity the braided ground strap has, and the bigger round wire gets, the harder it is to bend. If you look closely at the braided strap you will see that it too is comprised of many small gauge (diameter) wires braided together. The reason for this is that the electrons flow on the outside of conductors (wires) and the ability to conduct current is a surface area equation. Think of operating a starter motor as dumping out 8 oz. of Coca-Cola into the sink--you want as much of the soda to dump out as fast as you can. In one hand you have a drink glass (rock glass) full, the other a bottle of Coke. If you turned them both over at the same time which one is going to empty first? An undersized cable is, in effect a bottleneck.

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Both braided strap and welding cable use fine wire for two reasons. One, for flexibility and two, to increase the current density. With finer wire the strands can be packed tighter resulting in more copper per unit area. Either would work but braid would be more correct for the negative and round more correct for the positive.

Just to correct a misconception: At DC there is no "skin effect" in copper wire. The current density is uniform across the cross section no matter what the cross sectional area (wire AWG). It is only with high frequency AC that these effects need to be considered.

Assuming that the starter draws 300A while cranking, the wire is 3 feet long, and we want no more than 0.1V drop across the wire, then the resistance should be less than 0.1 milliohms per foot. 1 AWG is 0.126 milliohms per foot, 0 AWG is 0.1 milliohms per foot, and 00 AWG is 0.08 milliohms per foot. Any of these will work but as the length increases then the gauge must be reduced. The 1937 Buicks had the battery under the front seat and had longer cables and thus need a lower gauge wire.

Also, there may be as much or more resistance at the connections than in the wires so it is very important to make sure the terminals and connections are clean and tight.

Lastly, I had a condition where the solenoid was causing a large voltage drop. Inside the solenoid there is a large thick copper disc that gets pulled down to bridge two contacts to make the main high current connection to the starter windings. This carries the full 300A and mine was pitted and oxidized and caused a high voltage drop. I took the disc out, cleaned and burnished the contacts and turned the disc around, exposing the new unused side and it has been working fine for the past 20 years.

Steve D

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I've done the make-your-own cables with welding cable, and can suggest an easier alternative. Auto parts stores that stock truck battery cables (as others have said, on the industrial side of town) offer a wide selection of the big-diameter cables in any length you need. I now use these on my six-volt cars with no problems. Also as others have said, pay attention to the details of establishing a good ground. You can do a rough check of your valve timing by removing the valve cover and observing when the valves begin to open, compared to the position of the piston and flywheel, assuming that you have the factory specs on degrees before and after top dead center. To do this accurately you would probably need to remove the radiator and mount a degree wheel onto the front pulley/vibration damper. Another easy way to check is to connect a vacuum guage while the engine is running. If you're pulling 18 inches of vacuum or better, odds are the valve timing is correct. Something else you can check to help determine whether your engine is actually tight is whether you can rotate the engine fairly easily by prying against the flywheel teeth, or using a socket and breaker bar on the front pulley nut. You'd need to compare this against a known good engine, or just have some experience doing this. Let us know your progress.

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Boy, you guys are an absolute treasure trove of info!

I've got the Heavy cable (round, cloth wrapped) from the positive side heading down to the solenoid, and a braided ground strap. Both were purchased from Bob's. I will supplement them with the 00 cable and tell you if I see any improvement!

As far as timing goes, I am confident that my ignition timing is correct in respect to the crankshaft. I set initial ignition timing with a timing light.

So it sounds like nobody is worried about the 9 Vs. 11 chain links issue?

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Dear Tshabet:

I read all the excellent suggestions the guys have posted, but there's one obvious (and likely) suggestion missing about cause. You noted the engine was freshly rebuilt. Did they or you PAINT it? Paint is a good insulator. If the surfaces between the block and the flywheel housing were painted before assembly, you've got a problem. Same point for the mounting surface on the flywheel housing and the starter. All 4 of these surfaces want to be free of paint, oil, grease, and dry at assembly. Any resistance at these places is a killer.

Regards, Dave Corbin

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Hi Dave,

nope, the only paint present is the original factory coat. However, I do believe I will run a jumper from the ground strap attachment point on the coil bracket over to the body of the starter just to make sure I eliminate that as a potential cause.

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Aaron,

I am able to get the engine to turn over with a socket on the front pulley. It's very difficult since I'm working against the compression of the engine... not sure how "tight" it's supposed to feel.

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http://s129.photobucket.com/albums/p205/paulcougar50/?action=view&current=Buick10-30-05.flv

this video was taken by me october of '05. hadnt gotten it on the road yet. i put off the entire brake system redo it needed all summer, got it done over the winter. i think this was before i made those repairs to the starter and the copper solenoid contact points. still it was plenty enough to start it. note at at 1:53 that start goes faster because its warm and i think it was kinda flooded but not so much as to not fire at all. i believe i took this video to post on this forum back then to show everyone my pushrod movement and stuff, because a bunch of them didnt turn at all and got little oil. but it also shows how fast the car cranks. perhaps we can establish a reference point with this and now know what is actually SLOW versus FAST cranking! <img src="http://forums.aaca.org/images/graemlins/laugh.gif" alt="" />

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To all on this thread:

Normally, a well tuned and set engine should start at 50 RPM, which will seem very slow (less than 1 round per second). Most starters should be able to turn the engine about 150 RPM, which is 2-3 rounds per second. If you've ever been around a big diesel truck that has a compressed air starter, that starter will get a 855 inch Cummins to 1200 rpm in about 1/2 of a second, scaring the pants of of everyone in the vicinity that isn't expecting it!

Regards, Dave Corbin

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Paul, I for one would like to say thanks for that video. That was cool. I also have a question: under the valve cover, it looks like you have two (?) pipes running more-or-less the length of the head. Are they oil pipes? I can't tell from the view, and there's nothing like that in my valvetrain. Wonder if I'm missing something.

And Grant, I guess by now you've found out for yourself how much fun it is to get a socket on that crankshaft pulley. The radiator fins and fan blades are SHARP, aren't they? <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" /> But as Aaron says, definitely, pull the plugs; if it takes a lot of effort to turn it, it's pretty tight, but may just need to run in some.

Dan

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haha glad i could help ya out there!

is it POSSIBLE to get a socket on the crank pulley? Because its really becoming apparent that you HAVE done it. i took one look down there, then reached down there, then said "hmmm. nope, screw that." in much more vulgar terms. this was before i even first cranked the engine. ended up dumping marvel mystery oil in each cyl. waiting like 5 days, then hitting the pedal and praying. turned out well, actually as you might imagine.

about those lines, wow how nice the car has been since i yanked those P.O.S's!!!! one heck of a band aid, i found out, a very lazy fix, because removing the rocker shaft and cleaning out the crap really aint bad at all!!!

dumped way too much oil on the valve stems, smoked like a campfire trying to burn saturated wood! i HATED that so much, it really looked awful. who knows when it was done, id guess maybe sometime around when my dad got it, maybe with the first owner. 50/50 shot of getting it right, only two owners lol!

it actually starved the rocker-to-pushrod joints of a lot of much needed oil! now those are silent, and the stems seem to be too. thats my guess as to why it was put there. "my valves er noisy!" repair guy: "i got a great idea!!!!" <img src="http://forums.aaca.org/images/graemlins/crazy.gif" alt="" />

whatever, ive righted it though, and im proud of that.

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Paul:

Thanks so much for the video, lots of fun and great sights and sounds.

I would say that your Buick turns on the starter quite a bit faster than mine did right after rebuild. Your engine is certainly loose and well broken in. An engine with fresh bores, new rings and bearings, and zero run time should be quite a bit stiffer -- and probably will remain that way for the first 5K miles or so.

All the suggestions about cleaning up grounds, better cables, good battery, are good, but I would still expect the engine to be a bit sluggish until it is thoroughly broken in.

Ditto on overheating, most of my freshly rebuilt prewar engines have overheated badly in the summer when first put on the road. After a few thousand miles are accumulated, they get much better.

Bill

Albuquerque, NM

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Hey Paul, yeah, when I first reinstalled my engine, I put in the block/trans and got everything bolted up, then dropped the head down on top. So, had to set the valve lash with the engine in the car, turning by hand with a socket wrench. I think I was having to put the socket on the nut, then put the wrench on the socket, then a piece of pipe on the socket handle. Then of course the socket would fall off the nut, or the wrench off the socket, I'd cut up my knuckles some more, cuss, and so on. Pure fun, standing on a box and stretching over that big ol' fender. YOU know. Plus, I was doing this before I put the hood panels and hinge back on. Even less access for you and Grant. Again spoiled by my MG, which has a hand-crank like a Model T.

That's interesting, about your old oil pipes. Makes one wonder what issue they were trying to solve. I gotta tell ya, although I've spun the engine with the little pipe disconnected from the rocker shaft and know I have oil flow at that point, I'd feel better if I saw a little more oil flying around when it's running with the cover off. Just wonder if everything's ok for sure. If the valve guides are supposed to lubricate from oil coming down from the rockers, well, I don't know .....

Dan

(Grant, sorry to hijack your thread <img src="http://forums.aaca.org/images/graemlins/blush.gif" alt="" /> )

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No problem hijacking the thread, this stuff is really interesting!

I had the timing cover off of the car because I had a significant oil leak there, so when I started this thread I had the radiator out of the car...makes accessing the crank bolt MUCH easier!

Well, on Friday night I buttoned everything back up (hope nobody decides to pipe up that my timing chain is incorrect!) and, with my new heavier cables AND a jumper from the ground strap at the block to the starter body, I hit the starter: A WORLD of difference. Like night and day. It was actually cranking fast enough that I was able to easily start the engine and get it to idle, without using starting fluid. A first!

Of course, now I have a great idle but the engine dies as soon as I try to feed it some gas... seems like it must be running too lean and/or I have a problem with the accelerator pump. But that's another thread <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

Thanks again for all of the help guys!

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Grant, for what it's worth, I still have two half-empty cans of starter fluid in the trunk from before I rebuilt mine. Don't need 'em any more, I put a kit in the carb and the accelerator pump works great now, but darn it, I have the same issue as you when its cold - step on the throttle and it stalls, unless I floor it. I'm wondering if I don't have the choke set right and I'm flooding it with the pump with no air coming in. If you figure YOUR carb out first, let me know. And congratulations on correcting your cranking issue!

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ive gone up a few times this winter to run the car in its garage, and its VERY surprising how much fuel it needs at a cold start!!! wow. i figured i flooded it with starting fluid but it didnt run for 2 seconds, let alone long enough to pump the drained-down fuel up to the carb! had to literally push the spray nozzle on the can all the way down to keep it running. just a thought, and it just taught me an interesting lesson. when you think about it, it makes sense. at first theres NOTHING in the cylinders. and theres 8 of em. and its gotta go from a dead stop to about ~1k rpm.

its hard to burn down a big tree thats alive and moist with nothing but a match on a windy day, is how i see it!

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Grant, regarding that front-end oil leak, I'm with you. When I put the engine back together, I just kept the old timing chain (penny wise, pound foolish, I know). Had it reassembled, on sawhorses, ready to hook up the hoist, and went "NO!" and called Bob's for a new chain. Of course, I had to take off the timing cover, and didn't have a new gasket, thought I could take care of the torn-up spots with goop. Doesn't seem to have worked - it's leaking oil, from, I THINK, around the bolts. Tried stuffing in some sealant, not much help. Hoping as the engine breaks in the rings will seal so there's not so much crankcase pressure. In the meantime I've just stuffed a wad of paper towels up under there to soak up the oil. Lame, but there it is. Maybe I'll find the energy to take it back apart and cut a new gasket.

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Mine actually turned out to be leaking from the pan seal (between the oil pan and timing cover) rather than the timing cover gasket itself. We were flatbedding the car to its current garage space (rented) and when I was getting it off the truck, it started to hemmorhage a large amount of oil since the car was in a steep nose-down attitude. I ended up discovering that the oil pan gasket was pretty much trashed due to it bonding to the timing cover and getting torn up when the cover was removed. I ended up cutting a new gasket out of a roll of gasket material I had on hand, and using some gasket putty to shore it up. Seems to be working OK so far... If worse comes to worse, I'll just end up replacing the entire pan seal.

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